In 1808, Napoleon I decided to establish a map intended to replace that of Cassini; however during the empire, geographical engineers who were attributed to it had to achieve more precise work and first create a map of the battlefield. The implementation of this new map can begin with the first work from a triangulation supported on the meridian; one from Delambre and Méchain. Work of this map was spread out between 1817 and 1866, by testing several different scales. It was a map for the use of the soldiers: Geological Survey map, on the scale 1:80,000. This Geological Survey map was raised and drawn by the Deposit of the War ,then become the geographical’s Service of the army, and replaced later by the national geographical Institute (France)|National geographical institute (IGN) Institut géographique national (IGN)